Negotiations "have been suspended indefinitely to allow stakeholders time to reflect on the current offer," the world's top platinum producer Anglo American Platinum (Amplats) said in a statement.

The radical Amcu union, which represents tens of thousands of platinum workers, had appeared to soften its position on Tuesday, saying its wage demand could be spread over four years.

But mining companies said the new demand was just unrealistic and translated to an increase of up to 35% year-on-year over a four-year period.

Amplats, Impala Platinum (Implats) and Lonmin – the world's top three platinum producers – had offered staggered increases of 7% to 9% over the next three years. Their offer is well above the current South African inflation rate of 5.4%.

Amcu secretary general Jeff Mphahlele said however that the talks "have not been abandoned", adding he was waiting for the companies to respond formally to their offer.

The companies said they remain open to further talks to help end the strike, but warned that the union need to consider the economic realities.

"We are hopeful though that Amcu will come to recognise and appreciate the realities of the company's position and will work towards a solution that will benefit its members," said Griffith.

Amcu has threatened to widen the strike action that started on January 23. "We have done our utmost best – starting at R12 500 over one year, then we extended it to say pay over two years, three years and now we are at four years. They are still crying foul. We don't know what to do," said Mphahlele.

"We will intensify our strike," he said.

The union plans to march on the seat of government on Thursday to increase pressure on President Jacob Zuma.

South Africa holds around 80% of the world's known platinum reserves. – AFP